(meth)acrylate composition

ABSTRACT

Provided is a (meth)acrylate composition containing: (A) at least one (meth)acrylate compound selected from the group consisting of a (meth)acrylate-modified silicone oil, a (meth)acrylate having a long-chain aliphatic hydrocarbon group, and a polyalkylene glycol (meth)acrylate having number-average molecular weight of not less than 400; (B) a (meth)acrylate compound to which an alicyclic hydrocarbon group having 6 or more carbon atoms is ester-linked; (C) (meth)acrylic acid or a (meth)acrylate compound having a polar group; (D) a radical polymerization initiator; and (E) a white pigment.

TECHNICAL FIELD

The present invention relates to a composition which contains a(meth)acrylate compound, more specifically, to a composition suitablyused as a raw material of a reflective material for an opticalsemiconductor and to a cured product thereof.

BACKGROUND ART

Since 1990s, progress of a light-emitting diode (LED) is remarkablewhereby multicolor is progressing along with increase of output power.In particular, a white LED is expected to be a next generation lightsource to replace existing lamps such as a white lamp, a halogen lamp,and an HID lamp. In fact, an LED is valued in such characteristics asits long life, low power consumption, high heat stability, andlow-voltage drive. Therefore, it is used in a display, a destinationsign board, a car lamp, a signal light, an emergency light, a cellphone, a video camera, and so on. Such luminescent devices are usuallymanufactured by fixing an LED to a concave-shaped reflective materialformed of a synthetic resin integrally molded with a lead frame and thenby sealing it with a sealant such as an epoxy resin and a siliconeresin.

As the reflective material for the LED, a polyamide resin is widely usednowadays. However, the reflectance decreases after a long-term usage dueto the deterioration of the resin caused by increase of heat generationand optical intensity which is resulted from enhanced output power ofthe LED. Therefore, a measure to remedy this problem is desired.

To cope with this problem, for example, a reflective material made usinga silicone resin is proposed in Patent Documents 1 to 3 and a reflectivematerial made using an epoxy resin is proposed in Patent Document 4. Butnone of them has yet been used widely in practice. Especially when asilicone resin is used, problems are concerned in association withevaporation of a low molecular weight siloxane which may cause a contactmalfunction and penetration of water vapor into the luminescent devicewhich may cause damage to the light emitting element.

On the other hand, a reflective material made using a (meth)acrylateresin is disclosed in Patent Documents 5 and 6. In such reflectivematerial, hollow particles are used as a filler to increase reflectancein the ultraviolet light region. It is disclosed that high reflectancein the visible light region can be achieved by laminating the materialwith a material which has high visible light reflectance.

CITATION LIST Patent Literature

-   Patent Document 1: JP-A-2010-18786-   Patent Document 2: JP-A-2010-21533-   Patent Document 3: JP-A-2010-106243-   Patent Document 4: JP-A-2010-47740-   Patent Document 5: JP-A-2008-231231-   Patent Document 6: JP-A-2008-243892

SUMMARY OF INVENTION Technical Problem

In view of the situation as mentioned above, a reflective materialhaving high reflectance in the visible light region and the excellentadhesion with adjacent parts (lead frame and sealant) withoutreflectance decrease even after a long-term usage is desired.

Accordingly, the problem to be solved by the present invention is toprovide a (meth)acrylate composition which provides a cured producthaving high reflectance in the visible light region, the excellent heatresistance and light resistance, and the excellent adhesion withadjacent parts, thereby suitably used as a raw material of a reflectivematerial for an optical semiconductor.

Solution to Problem

The present inventors carried out an extensive investigation and as aresult, found that the above problem is solved by a compositioncontaining a certain acrylate compound. The present invention wasaccomplished based on this finding.

That is, the present invention provides a (meth)acrylate composition, acured product, and a reflective material, as shown below.

[1] A (meth)acrylate composition comprising:

(A) at least one (meth)acrylate compound selected from the groupconsisting of a (meth)acrylate-modified silicone oil, a (meth)acrylatehaving a long-chain aliphatic hydrocarbon group, and a polyalkyleneglycol (meth)acrylate having number-average molecular weight of not lessthan 400,

(B) a (meth)acrylate compound to which an alicyclic hydrocarbon grouphaving 6 or more carbon atoms is ester-linked,

(C) (meth)acrylic acid or a (meth)acrylate compound having a polargroup,

(D) a radical polymerization initiator, and

(E) a white pigment.

[2] The (meth)acrylate composition according to [1], wherein

the amount of the component (A) is 5 to 90% by mass, the amount of thecomponent (B) is 5 to 90% by mass, and the amount of the component (C)is 0.5 to 50% by mass, based on totality of the components (A), (B) and(C), and

the amount of the component (D) is 0.01 to 10 parts by mass and theamount of the component (E) is 3 to 200 parts by mass, relative to 100parts by mass of totality of the components (A), (B) and (C).

[3] The (meth)acrylate composition according to [1] or [2], wherein thecomponent (A) is a (meth)acrylate having an aliphatic hydrocarbon groupwith 12 or more carbon atoms and/or a polyalkylene glycol (meth)acrylatehaving number-average molecular weight of not less than 400.[4] The (meth)acrylate composition according to any of [1] to [3],wherein the component (A) is hydrogenated polybutadienedi(meth)acrylate, hydrogenated polyisoprene di(meth)acrylate, and/orpolyethylene glycol di(meth)acrylate having number-average molecularweight of not less than 400.[5] The (meth)acrylate composition according to any of [1] to [4],wherein the component (B) is a (meth)acrylate compound which isester-linked with at least one alicyclic hydrocarbon group selected fromthe group consisting of adamantyl, norbornyl, isobornyl,dicyclopentanyl, and cyclohexyl.[6] The (meth)acrylate composition according to any of [1] to [5],wherein the component (C) is a (meth)acrylate compound having a polargroup selected from the group consisting of hydroxyl, epoxy, glycidylether, tetrahydrofurfuryl, isocyanate, carboxyl, alkoxysilyl, phosphateester, lactone, oxetane, and tetrahydropyranyl.[7] A cured product obtained by curing the (meth)acrylate compositionaccording to any of [1] to [6].[8] A reflective material made using the cured product according to [7].[9] The reflective material according to [8], wherein the reflectivematerial is a reflective material for an optical semiconductor.

Advantageous Effects of Invention

The (meth)acrylate composition of the present invention provides a curedproduct having high reflectance in the visible light region with theexcellent whiteness, the excellent heat resistance and light resistance,and with less yellowing, and having the excellent adhesion with adjacentparts (especially with a lead frame), thereby suitably used as a rawmaterial of a reflective material for an optical semiconductor.

A reflective material made using the cured product obtained by curingthe (meth)acrylate composition of the present invention does notdecrease in its reflectance even after a long-term usage, while havinghigh reflectance in the visible light region and the excellent adhesionwith adjacent parts.

DESCRIPTION OF EMBODIMENTS [(Meth)Acrylate Composition]

The (meth)acrylate composition of the present invention contains:

(A) at least one (meth)acrylate compound selected from the groupconsisting of a (meth)acrylate-modified silicone oil, a (meth)acrylatehaving a long-chain aliphatic hydrocarbon group, and a polyalkyleneglycol (meth)acrylate having number-average molecular weight of not lessthan 400,

(B) a (meth)acrylate compound to which an alicyclic hydrocarbon grouphaving 6 or more carbon atoms is ester-linked,

(C) (meth)acrylic acid or a (meth)acrylate compound having a polargroup,

(D) a radical polymerization initiator, and

(E) a white pigment.

<Component (A)>

The component (A) used in the composition of the present invention is atleast one (meth)acrylate compound selected from the group consisting ofa (meth)acrylate-modified silicone oil, a (meth)acrylate having along-chain aliphatic hydrocarbon group, and a polyalkylene glycol(meth)acrylate having number-average molecular weight of not less than400. Since the composition of the present invention contains thecomponent (A), mainly flexibility is achieved so that formation of acrack may be suppressed.

((Meth)Acrylate-Modified Silicone Oil)

The (meth)acrylate-modified silicone oil used in the present inventionis a compound which has an acryl group and/or a methacryl group at itsterminal, and preferably contains a dialkyl polysiloxane in thebackbone. This (meth)acrylate-modified silicone oil is a modifiedcompound of dimethyl polysiloxane in many cases, but all or a part ofthe alkyl groups in the dialkyl polysiloxane backbone may be substitutedwith a phenyl group or an alkyl group other than a methyl group in placeof the methyl group. Examples of the alkyl group other than the methylgroup include an ethyl group and a propyl group. As the commerciallyavailable products of such compound, a single-end reactive silicone oil(for example, X-22-174DX, X-22-2426, and X-22-2475), a dual-end reactivesilicone oil (for example, X-22-164A, X-22-164C, and X-22-164E) (all ofthe above are tradenames and are manufactured by Shin-Etsu Chemical Co.,Ltd.), a methacrylate-modified silicone oil (for example, BY16-152D,BY16-152, and BY16-152C) (all of the above are tradenames and aremanufactured by Dow Corning Toray Co., Ltd.), and the like may be used.

In addition, as a (meth)acrylate-modified silicone oil, a polydialkylsiloxane having an acryloxyalkyl terminal or a methacryloxyalkylterminal may be used. Specific examples thereof includemethacryloxypropyl-terminated polydimethylsiloxane,(3-acryloxy-2-hydroxypropyl)-terminated polydimethylsiloxane, an ABAtype triblock copolymer of acryloxy-terminated ethylene oxidedimethylsiloxane (A block) and ethylene oxide (B block), andmethacryloxpropyl-terminated branched polydimethylsiloxane.

Among them, in view of adhesion of the cured product,(3-acryloxy-2-hydroxypropyl)-terminated polydimethylsiloxane and an ABAtype triblock copolymer of acryloxy-terminated ethylene oxidedimethylsiloxane (A block) and ethylene oxide (B block) are suitablyused.

((Meth)Acrylate Having a Long-Chain Aliphatic Hydrocarbon Group)

The (meth)acrylate having a long-chain aliphatic hydrocarbon group usedin the present invention is a compound having a (meth)acrylate groupbonded to a residue after a hydrogen atom is removed from a long-chainaliphatic hydrocarbon compound.

As to the aliphatic hydrocarbon compound that can derive the(meth)acrylate having a long-chain aliphatic hydrocarbon group used inthe present invention is preferably an alkane, in view of adhesion ofthe cured product of the present invention, an alkane having 12 or morecarbon atoms being more preferable.

In view of adhesion of the cured product of the present invention, thelong-chain aliphatic hydrocarbon group is more preferably an aliphatichydrocarbon group having 12 or more carbon atoms. By using the(meth)acrylate containing a long-chain aliphatic hydrocarbon grouphaving 12 or more carbon atoms as the component (A), the composition ofthe present invention can provide the cured product with the excellentadhesion.

In the (meth)acrylate having a long-chain aliphatic hydrocarbon groupused in the present invention, number of the (meth)acrylate group is notparticularly limited and one or a plurality of the groups may beallowed. When there is one (meth)acrylate group, the long-chainaliphatic hydrocarbon group is preferably a long-chain alkyl group, morepreferably an alkyl group having 12 or more carbon atoms (preferably 12to 24 carbon atoms, more preferably 12 to 18 carbon atoms). When thereare two (meth)acrylate groups, the long-chain aliphatic hydrocarbongroup is preferably a long-chain alkylene group, more preferably analkylene group having 12 or more carbon atoms (preferably 12 to 24carbon atoms, more preferably 12 to 18 carbon atoms).

Specific examples of the alkyl group having 12 or more carbon atomsinclude dodecyl (including lauryl), tetradecyl, hexadecyl, octadecyl(including stearyl), eicosyl, triacontyl, and tetracontyl.Alternatively, the alkyl group having 12 or more carbon atoms may be analkyl group derived from a hydrogenated product of polybutadiene,polyisoprene, and the like. Specific examples of the alkylene grouphaving 12 or more carbon atoms include a divalent residue resulted byremoving hydrogen atoms from the foregoing alkyl groups.

Specific examples of the (meth)acrylate having a long-chain aliphatichydrocarbon group include an acryl or a methacryl compound having ahydrogenated polybutadiene backbone or a hydrogenated polyisoprenebackbone, such as hydrogenated polybutadiene di(meth)acrylate andhydrogenated polyisoprene di(meth)acrylate, or stearyl methacrylate.Among them, in view of adhesion of the cured product, hydrogenatedpolybutadiene di(meth)acrylate and hydrogenated polyisoprenedi(meth)acrylate are preferable.

(Polyalkylene Glycol (Meth)Acrylate Having Number-Average MolecularWeight of not Less than 400)

By using the polyalkylene glycol (meth)acrylate having number-averagemolecular weight of not less than 400 as the component (A), thecomposition of the present invention can provide a cured product withthe excellent toughness and adhesion. In the polyalkylene glycol(meth)acrylate having number-average molecular weight of not less than400 used in the present invention, number of the (meth)acrylate group isnot particularly limited and one or plurality of the groups may beallowed.

Specific examples of the polyalkylene glycol (meth)acrylate havingnumber-average molecular weight of not less than 400 includepolyethylene glycol di(meth)acrylate, polypropylene glycoldi(meth)acrylate, polybutylene glycol di(meth)acrylate, ethoxylatedtrimethylolpropane tri(meth)acrylate, and ethoxylated pentaerythritoltetra(meth)acrylate. Among them, in view of toughness and adhesion,polyethylene glycol di(meth)acrylate is preferable.

In view of toughness and adhesion as well as compatibility with thecomponent (B), the number-average molecular weight of such compound ispreferably 400 to 10,000, more preferably 450 to 5,000, still morepreferably 500 to 3,000.

In the present invention, as the component (A), at least one selectedfrom the (meth)acrylate-modified silicone oils, at least one selectedfrom the (meth)acrylates having a long-chain aliphatic hydrocarbongroup, or at least one selected from the polyalkylene glycol(meth)acrylates having number-average molecular weight of not less than400 may be used. Alternatively, a combination of the compoundsappropriately selected from the (meth)acrylate-modified silicone oils,the (meth)acrylates having a long-chain aliphatic hydrocarbon group, andthe polyalkylene glycol (meth)acrylates having number-average molecularweight of not less than 400 may be used.

Content of the component (A) in the composition of the present inventionis preferably 5 to 90% by mass, more preferably 15 to 80% by mass, stillmore preferably 20 to 70% by mass, based on totality of the components(A), (B) and (C), in view of toughness and adhesion.

<Component (B)>

The component (B) used in the composition of the present invention is a(meth)acrylate compound to which an alicyclic hydrocarbon group having 6or more carbon atoms is ester-linked.

As will be mentioned later, it is preferable that viscosity of a mixedsolution of the components (A) to (C) be higher in view ofdispersibility of a white pigment as the component (E). However, if ahighly viscous monomer (for example, hydrogenated polybutadienediacrylate) is used as the component (A), hardness of the cured productdecreases. Therefore, it is preferable to combine it with a monomerwhich leads to a polymer having a high glass transition temperature(Tg). Accordingly, in view of the above-mentioned aspect, a(meth)acrylate having a substituent with an alicyclic structure ispreferred to a (meth)acrylate having a substituent with a linear orbranched structure as the component (B), because the former leads to apolymer with higher Tg than the latter.

Further, in the composition of the present invention, by using the(meth)acrylate having an alicyclic hydrocarbon group with 6 or morecarbon atoms as the component (B), the cured product thereof isexcellent in its hardness, heat resistance, and light resistance. Inaddition, because the ester substituent is an alicyclic hydrocarbongroup not containing an aromatic group and the like, deteriorationthereof by an ultraviolet light is unlikely to occur.

Specific examples of the alicyclic hydrocarbon group having 6 or morecarbon atoms in such compounds include cyclohexyl, 2-decahydronaphthyl,adamantyl, 1-methyladamantyl, 2-methyladamantyl, biadamantyl,dimethyladamantyl, norbornyl, 1-methyl-norbornyl,5,6-dimethyl-norbornyl, isobornyl, tetracyclo[4.4.0.12,5.17,10]dodecyl,9-methyl-tetracyclo[4.4.0.12,5.17,10]dodecyl, bornyl, anddicyclopentanyl. Among them, in view of hardness, heat resistance, andlight resistance of the cured product thereof, cyclohexyl, adamantyl,norbornyl, isobornyl, and dicyclopentanyl are preferable, adamantylbeing more preferable, and 1-methyladamantyl being still morepreferable.

Specific examples of the (meth)acrylate compound having the alicyclichydrocarbon group in the component (B) include cyclohexyl(meth)acrylate, 1-adamantyl (meth)acrylate, norbornyl (meth)acrylate,isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. In thepresent invention, these (meth)acrylate compounds may be used alone orin a combination of two or more kinds as the component (B).

Meanwhile, since the viscosity of a monomer which leads to a polymerhaving high Tg is generally low, it is preferable that a monomer whichleads to a polymer having a further higher Tg be used to avoid decreasein viscosity of a mixed solution of the components (A) to (C). By usingthe monomer which leads to a polymer having a further higher Tg, smallercontent thereof in the composition may be used so that hardness of thecured product can be made higher without decreasing viscosity of thesolution. In view of the above-mentioned aspect, a (meth)acrylate havingan adamantane structure which provides a polymer having high Tg ispreferable as the component (B), 1-adamantyl (meth)acrylate beingparticularly preferable.

In view of harness, heat resistance, and light resistance, content ofthe component (B) in the composition of the present invention ispreferably 5 to 90% by mass, more preferably 10 to 80% by mass, stillmore preferably 20 to 70% by mass, based on totality of the components(A), (B) and (C).

<Component (C)>

The component (C) used in the composition of the present invention is(meth)acrylic acid or a (meth)acrylate compound having a polar group.Since these compounds have a polar character, adhesion with metalsurface and the like having a polar character is improved due to aformation of a hydrogen bond and the like by incorporating the component(C) into the composition of the present invention. In addition,wettability thereof is improved owing to the presence of the polargroup. Meanwhile, although an alkylene glycol group may be involved ingiving of adhesion, an alkylene glycol (meth)acrylate shall not beincluded in the component (C).

((Meth)Acrylate Compound Having a Polar Group)

As the (meth)acrylate compound having a polar group, (meth)acrylatecompounds having a substituent containing an atom other than carbon andhydrogen ester-linked thereto are exemplified. Examples of thesubstituent include hydroxyl, epoxy, glycidyl ether, tetrahydrofurfuryl,isocyanate, carboxyl, alkoxysilyl, phosphate ester, lactone, oxetane,tetrahydropyranyl, and amino.

Specific examples of the (meth)acrylate compound having a polar groupinclude 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate (forexample, tradename: 4-HBA, manufactured by Nippon Kasei Chemical Co.,Ltd.), cyclohexanedimethanol mono(meth)acrylate (for example, tradename:CHMMA, manufactured by Nippon Kasei Chemical Co., Ltd.), glycidyl(meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether (for example,tradename: 4-HBAGE, manufactured by Nippon Kasei Chemical Co., Ltd.),tetrahydrofurfuryl (meth)acrylate, 2-isocyanatoethyl (meth)acrylate,2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethylhexahydrophthalate, 3-(meth)acryloxypropyl trimethoxy silane,3-(meth)acryloxypropyl methyl dimethoxy silane, 3-(meth)acryloxypropyltriethoxy silane, 3-(meth)acryloxypropyl methyl diethoxy silane,2-(meth)acryloyloxyethyl phosphate,di(2-(meth)acryloyloxyethyl)phosphate, KAYAMER PM-21 (tradename,manufactured by Nippon Kayaku Co., Ltd.), γ-butyrolactone(meth)acrylate, (meth)acrylic acid (3-methyl-3-oxetanyl), (meth)acrylicacid (3-ethyl-3-oxetanyl), tetrahydrofurfuryl (meth)acrylate,dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate.

In the present invention, at least one selected from the foregoing(meth)acrylic acids, or at least one selected from the foregoing(meth)acrylate compounds having the polar group may be used as thecomponent (C), Alternatively, a combination of appropriately selectedcompounds from the foregoing (meth)acrylic acids and the foregoing(meth)acrylate compounds having the polar group may be used.

Content of the component (C) in the composition of the present inventionis preferably 0.5 to 50% by mass, more preferably 1 to 40% by mass,still more preferably 3 to 20% by mass, based on totality of thecomponents (A), (B) and (C), in view of adhesion.

<Component (D)>

The component (D) used in the composition of the present invention is aradical polymerization initiator.

Although the radical polymerization initiator is not particularlylimited, specific examples thereof include ketone peroxides,hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, alkylperesters (peroxyesters), and peroxy carbonates.

Specific examples of the ketone peroxide include methyl ethyl ketoneperoxide, methyl isobutyl ketone peroxide, acetylacetone peroxide,cyclohexanone peroxide, and methylcyclohexanone peroxide.

Specific examples of the hydroperoxide include 1,1,3,3-tetramethylbutylhydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, p-menthanehydroperoxide, and diisopropylbenzene hydroperoxide.

Specific examples of the diacyl peroxide include diisobutyryl peroxide,bis-3,5,5-trimethylhexanol peroxide, dilauroyl peroxide, dibenzoylperoxide, m-toluoyl benzoyl peroxide, and succinic acid peroxide.

Specific examples of the dialkyl peroxide include dicumyl peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,1,3-bis(t-butylperoxyisopropyl)hexane, t-butylcumyl peroxide, di-t-butylperoxide, di-t-hexyl peroxide, and2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

Specific examples of the peroxyketal include1,1-di-t-hexylperoxy-3,3,5-trimethylcyclohexane,1,1-di-t-hexylperoxycyclohexane,1,1-di-t-butylperoxy-2-methylcyclohexane,1,1-di-t-butylperoxycyclohexane, 2,2-di(t-butylperoxy)butane, and butyl4,4-bis-t-butylperoxypentanoate.

Specific examples of the alkyl perester (peroxy esters) include1,1,3,3-tetramethylbutylperoxy neodecanoate, α-cumylperoxy neodecanoate,t-butylperoxy neodecanoate, t-hexylperoxy neodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxy pivalate, t-butylperoxy pivalate,1,1,3,3-tetramethylbutylperoxy-2-ethyl hexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethyl hexanoate, t-butylperoxy isobutyrate,di-t-butylperoxy hexahydroterephthalate,1,1,3,3-tetramethylbutylperoxy-3,5,5-trimethyl hexanoate,t-amylperoxy-3,5,5-trimethyl hexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy acetate, t-butylperoxy benzoate,dibutylperoxytrimethyl adipate,2,5-dimethyl-2,5-di-2-ethylhexanoylperoxyhexane, t-hexylperoxy-2-ethylhexanoate, t-hexylperoxy isopropyl monocarbonate, t-butylperoxy laurate,t-butylperoxy isopropyl monocarbonate, t-butylperoxy-2-ethylhexylmonocarbonate, and 2,5-dimethyl-2,5-di-benzoylperoxyhexane.

Specific examples of the peroxy carbonate include di-n-propylperoxydicarbonate, diisopropylperoxy carbonate, di-4-t-butylcyclohexylperoxycarbonate, di-2-ethylhexylperoxy carbonate, di-sec-butylperoxycarbonate, di-3-methoxybutylperoxy dicarbonate, di-2-ethylhexylperoxydicarbonate, diisopropyloxy dicarbonate, t-amylperoxy isopropylcarbonate, t-butylperoxy isopropyl carbonate, t-butylperoxy-2-ethylhexylcarbonate, and 1,6-bis(t-butylperoxycarboxyloxy)hexane.

Alternatively, a photo-radical polymerization initiator may be used asthe radical polymerization initiator of the component (D). As thecommercially available product of the radical polymerization initiator,IRGACURE 651, IRGACURE 184, DAROCUR 1173, IRGACURE 2959, IRGACURE 127,IRGACURE 907, IRGACURE 369, IRGACURE 379, DAROCUR TPO, IRGACURE 819, andIRGACURE 784 (all of these are tradenames and are manufactured by BASFSE), and the like may be used.

In the present invention, these radical polymerization initiators of thecomponent (D) may be used alone or in a combination of two or morekinds.

Content of the component (D) in the composition of the present inventionis preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 partsby mass, relative to 100 parts by mass of totality of the components(A), (B) and (C), in view of polymerization reactivity.

<Component (E)>

The component (E) used in the composition of the present invention is awhite pigment. Incorporating the component (E) into the composition ofthe present invention allows to make the cured product white and toincrease reflectance in the visible light region.

Specific examples of the white pigment include titanium dioxide,alumina, zirconium oxide, zinc sulfide, zinc oxide, magnesium oxide,silica, potassium titanate, barium sulfate, calcium carbonate, andsilicone particle. Among them, titanium dioxide is preferable in view ofhigh reflectance and availability. Among two crystal types of titaniumdioxide, rutile and anatase, the rutile type is preferable in thepresent invention because the anatase type may cause deterioration of aresin due to its photocatalytic function.

Average particle diameter of the white pigment in the composition of thepresent invention is preferably in the range of 0.01 to 0.5 μm, morepreferably 0.1 to 0.4 still more preferably 0.15 to 0.3 μm in view ofdispersibility of the white pigment.

Furthermore, the white pigment may be hollow particles. In the case thatthe white pigment is hollow particles, a visible light passing throughan outer shell of the hollow particle is reflected in the hollow part.Therefore, it is preferable that difference between the refractiveindexes of the constituent of the hollow particle and gas present in thehollow particle be large in order to increase reflectance in the hollowpart. The gas present in the hollow particle is usually air; but inertgas such as nitrogen and argon may be used, or inside the hollowparticle may be vacuum.

In addition, the white pigment may be optionally surface-treated with asilicon compound, an aluminum compound, an organic substance, and so on.Examples of the treatment include an alkylation treatment, atrimethylsilyl treatment, a silicone treatment, and a treatment by acoupling agent. The white pigment of the component (E) may be used aloneor in a combination of two or more kinds.

Content of the component (E) in the composition of the present inventionis preferably 1 to 200 parts by mass, more preferably 3 to 150 parts bymass, still more preferably 5 to 100 parts by mass, relative to 100parts by mass of totality of the components (A), (B) and (C), in view ofreflectance and mechanical strength.

<Component (F)>

The composition of the present invention may contain a (meth)acrylatecompound other than the components (A) to (C) as the component (F)within the range not adversely affecting the effect of the presentinvention, in view of mechanical strength.

Specific examples of the (meth)acrylate compound of the component (F)include ethylene glycol di(meth)acrylate, propylene glycoldi(meth)acrylate, 1,4-butanediol (meth)acrylate, 1,6-hexanedioldi(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyldioldi(meth)acrylate, polyethylene glycol di(meth)acrylate and polypropyleneglycol di(meth)acrylate having number-average molecular weight of lessthan 400, an alkoxypolyalkylene glycol (meth)acrylate such asmethoxypolyethylene glycol methacrylate, ethylene oxide-modifiedbisphenol A di(meth)acrylate, propylene oxide-modified bisphenol Adi(meth)acrylate, epichlorohydrin-modified bisphenol A di(meth)acrylate,propylene oxide-modified glycerin tri(meth)acrylate, trimethylolpropanetri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate,dipentaerythrirol hexa(meth)acrylate,tris(acryloyloxyethyl)isocyanurate, and methoxypolyethylene glycol(meth)acrylate.

The foregoing (meth)acrylate compounds of the component (F) may be usedalone or in a combination of two or more kinds.

Content of the component (F) in the composition of the present inventionis preferably 100 or less parts by mass, more preferably 50 or lessparts by mass, relative to 100 parts by mass of totality of thecomponents (A), (B) and (C), in view of not adversely affecting theeffect of the present invention.

<Additive>

The composition of the present invention may further contain anyadditives such as an antioxidant, a photo-stabilizer, a UV absorber, aplasticizer, an inorganic filler, a coloring material, an antistaticagent, a lubricating agent, a mold releasing agent, and a flameretardant, within the range not adversely affecting the effect of thepresent invention.

(Antioxidant)

Examples of the antioxidant include a phenol antioxidant, a phosphorusantioxidant, a sulfur antioxidant, a vitamin antioxidant, a lactoneantioxidant, and an amine antioxidant.

Examples of the phenol antioxidant includetetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane,stearyl β-(3,5-di-t-butyl-4-hydroxyphenyl) propionate ester,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,tris[(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl]isocyanurate,2,6-di-t-butyl-4-methylphenol,3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane,and tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate.Commercially available products, for example, such as IRGANOX 1010,IRGANOX 1076, IRGANOX 1330, IRGANOX 3114, IRGANOX 3125, and IRGANOX 3790(all of them are manufactured by BASF SE); CYANOX 1790 (manufactured byCyanamid Corp.); SUMILIZER BHT and SUMILIZER GA-80 (both aremanufactured by Sumitomo Chemical Co., Ltd.) (all of the above-mentionedare tradenames), and the like may be used.

Examples of the phosphorus antioxidant includetris(2,4-di-t-butylphenyl) phosphite,2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-ethyl]ethanamine,cyclic neopentanetetrayl bis(2,6-di-t-butyl-4-methylphenyl)phosphite,and distearyl pentaerythritol diphosphite. Commercially availableproducts, for example such as IRGAFOS 168, IRGAFOS 12, and IRGAFOS 38(these are manufactured by BASF SE); ADK STAB 329K, ADK STAB PEP36, andADK STAB PEP-8 (these are manufactured by ADEKA Corp.); Sandstab P-EPQ(manufactured by Clariant SE); and Weston 618, Weston 619G, andWeston-624 (these are manufactured by GE Company) (all of theabove-mentioned are tradenames), and the like may be used.

Examples of the sulfur antioxidant include dilauryl thiodipropionate,distearyl thiodipropionate, dimyristyl thiodipropionate, lauryl stearylthiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), andpentaerythritol tetrakis(3-laurylthiopropionate). Commercially availableproducts, for example, such as DSTP “Yoshitomi”, DLTP “Yoshitomi”,DLTOIB, and DMTP “Yoshitomi” (all of them are manufactured by APICorp.); Seenox 412S (manufactured by SHIPRO KASEI KAISHA, Ltd.); Cyanox1212 (manufactured by Cyanamid Corp.); and SUMILIZER TP-D (manufacturedby Sumitomo Chemical Co., Ltd.) (all of the above-mentioned aretradenames), and the like may be used.

Examples of the vitamin antioxidant include tocopherol and2,5,7,8-tetramethyl-2-(4′,8′,12′-trimethyltridecyl)coumarone-6-ol anexample of the commercially available product including IRGANOX E201(tradename; manufactured by BASF SE).

Lactone antioxidant shown in JP-7-233160A and JP-7-247278A may be used.Alternatively, HP-136 (tradename for5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofurane-2-one, manufacturedby BASF SE) and the like may also be used.

Examples of the commercially available amine antioxidant includeIRGASTAB FS 042 (manufactured by BASF SE) and GENOX EP (chemical name ofdialkyl-N-methylamine oxide, manufactured by Crompton Corp.) (all of theabove-mentioned are tradenames).

These antioxidants may be used alone or in a combination of two or morekinds.

Content of the antioxidant in the composition of the present inventionis preferably 0.005 to 5 parts by mass, more preferably 0.02 to 2 partsby mass, relative to 100 parts by mass of totality of the components(A), (B) and (C), in view of not adversely affecting the effect of thepresent invention.

(Photo-Stabilizer)

Although any photo-stabilizers may be used, a hindered aminephoto-stabilizer is preferable. Specific examples thereof include ADKSTAB LA-52, LA-57, LA-62, LA-63, LA-67, LA-68, LA-77, LA-82, LA-87, andLA-94 (all of them are manufactured by ADEKA Corp.); Tinuvin 123, 144,440, 662, 765, and 770DF, and Chimassorb 2020, 119, and 944 (all of themare manufactured by BASF SE); Hostavin N30 (manufactured by Hoechst SE);Cyasorb UV-3346 and UV-3526 (both are manufactured by Cytech, Inc.);Uval 299 (manufactured by GLC Corp.); and Sanduvor PR-31 (manufacturedby Clariant SE) (all of the above-mentioned are tradenames).

These photo-stabilizers may be used alone or in a combination of two ormore kinds.

Content of the photo-stabilizer in the composition of the presentinvention is preferably 0.005 to 5 parts by mass, more preferably 0.002to 2 parts by mass, relative to 100 parts by mass of totality of thecomponents (A), (B) and (C), in view of not adversely affecting theeffect of the present invention.

[Method for Producing (Meth)Acrylate Composition]

The composition of the present invention may be obtained by mixing theforegoing component (A), component (B), component (C), component (D),component (E) and optionally component (F) and an additive.

The (meth)acrylate compounds of the components (A) to (C) are liquid;and therefore, when the white pigment of the component (E) is mixedthereinto for dispersion, the white pigment tends to precipitate ifviscosity of the liquid is low, thereby causing inhomogeneous color inthe cured product by precipitation of the white pigment prior to curingof the composition. This is undesirable for the performance of thereflective material. In view of this, viscosity of the mixture solutionof the components (A) to (C) is preferably 50 mPa·s or higher, morepreferably 100 mPa·s or higher, still more preferably 200 mPa·s orhigher. Since a monomer with high viscosity (for example, hydrogenatedpolybutadiene diacrylate) is contained in the component (A) used in thepresent invention, viscosity of the liquid may be increased by usingsuch a compound. If a monomer with high viscosity is not used, theproblem may be addressed by stirring the monomer composition in thevessel during the time of molding such as transfer molding or pressmolding as will be mentioned later.

Order of addition of each component may be determined as needed withinthe range not adversely affecting the effect of the present invention.For example, it is preferable that the white pigment of the component(E) be mixed and dispersed in the mixture after preparing a mixedsolution of the components (A) to (D) and optionally the component (F)and an additive, thereby preparing the composition, in view of uniformlydispersing the white pigment of the component (E) in the composition.

Since the white pigment is more difficult to disperse in a more viscoussolution, a rough surface or decrease in mechanical strength of thecured product may occur due to the presence of agglomerated particles.In this case, the white pigment may be well dispersed in a highlyviscous solution by first adding the white pigment of the component (E)to less viscous components among the components (A) to (C) to prepare amixed solution, followed by adding and mixing the more viscous component(A) thereinto.

A means to mix the respective components is not particularly limited andany stirrers (mixers) may be used.

Meanwhile, a mixer having a high mixing performance generally generatesheat during the time of mixing so that curing may take place duringmixing when the mixer is used with addition of the component (D).Therefore, in the case that a mixer having a high mixing performance isused, it is preferable that, after the components (A) to (C) and thecomponent (E) are mixed by the mixer having a high mixing performance,the component (D) be added and mixed by stirring to the extent not togenerate heat.

[Cured Product and Reflective Material]

The composition of the present invention gives a cured product by aradical polymerization reaction by heating the composition above thetemperature to generate a radical from the component (D) (in the case ofa photo-radical polymerization initiator, by irradiation with a lighthaving a sufficient energy to generate a radical). Conditions for curingmay be determined as needed by considering decomposition characteristicsand so on of the polymerization initiator. The cured product obtained bycuring the composition of the present invention is used suitably as amaterial for a reflective material.

The reflective material of the present invention may be produced bytransfer molding or press molding by using the polymerizable compositionof the present invention.

In the case of transfer molding, molding may be done by using a transfermolding machine with the conditions of, for example, molding pressure of5 to 20 N/mm², molding temperature of 120 to 190° C., and molding timeof 30 to 500 seconds; preferably molding temperature of 150 to 185° C.and molding time of 30 to 180 seconds. In the case of press molding,molding may be done by using a compression molding machine with theconditions of, for example, molding temperature of 120 to 190° C. andmolding time of 30 to 600 seconds; preferably molding temperature of 130to 160° C. and molding time of 30 to 300 seconds. In any of the moldingmethods, post-curing may be done, for example, at 150 to 185° C. for 0.5to 24 hours.

Alternatively, a molded article may be obtained by liquid resininjection molding, insert molding, potting processing, coatingprocessing, and the like. In addition, a molded article may be obtainedby a method similar to molding of a photo-curable resin, such as byUV-cure molding. When the polymerizable composition of the presentinvention is molded by transfer molding, press molding, liquid resininjection molding, insert molding, potting processing, coatingprocessing, and the like, pre-polymerization may be done.

The reflective material of the present invention has the excellentadhesion with adjacent parts such as a lead frame and a sealant.Breaking stress of the reflective material of the present inventionmeasured by the adhesion test described in EXAMPLES is preferably 5.0MPa or more, more preferably 5.5 MPa or more, still more preferably 7.0MPa or more.

Meanwhile, adhesion with a sealant may be further enhanced by anactivating the surface of the article with a treatment such asUV-irradiation, ozone exposure, plasma exposure, corona discharge,high-pressure discharge, and the like, after molding the reflectivematerial of the present invention.

The reflective material of the present invention has high reflectance inthe visible light region with small decrease of reflectance even after along-term usage. Photo-reflectance of the reflective material of thepresent invention at 450 nm wavelength is, as its initial value,preferably 85% or more, more preferably 90% or more, still morepreferably 95% or more; and after the deterioration test at 150° C. for1,000 hours, photo-reflectance of preferably 80% or more, morepreferably 85% or more, still more preferably 90% or more may beaccomplished. Meanwhile, photo-reflectance is measured by the methoddescribed in EXAMPLES.

The reflective material of the present invention may be used for a lampreflector of a liquid crystal display, a showcase reflective board, areflective board of various illumination apparatuses, a reflectivematerial for LED, and so on, being especially suitable for a reflectivematerial for an optical semiconductor.

EXAMPLES

Then, the present invention will be explained in more detail byEXAMPLES; however, the present invention is not restricted at all bythese EXAMPLES.

Methods for evaluation of physical properties of the cured productobtained in each of examples and comparative examples are as follows.

(1) Adhesion Test

Two silver-plated metal plates widely used in a lead frame (width of 20mm, length of 80 mm, and thickness of 0.3 mm) were piled up withoverlapping of 2 cm. Onto this overlapped area was applied eachcomposition solution obtained by Examples or Comparative Examples andwas cured to obtain a test piece. Then, the tensile shear adhesionstrength thereof (breaking stress; the maximum stress at the time ofbreaking) was measured according to JIS K6850. As the measurementinstrument, a tensile tester Autograph equipped with a controlledtemperature bath (tradename: AG-10, manufactured by Shimadzu Corp.) wasused.

<Measurement Conditions>

Measurement temperature: 23° C., humidity: 50% RH, tensile speed: 20mm/minute, and tensile load: 10 kN (load cell)

(2) Measurement of Photo-Reflectance

Photo-reflectance of the cured test piece was measured with anautographic spectrophotometer (tradename: UV-2400 PC, manufactured byShimadzu Corp.) equipped with a large multipurpose chamber unit for atest piece (tradename: MPC-2200, manufactured by Shimadzu Corp.). Afterthe initial value of photo-reflectance of the cured test piece wasmeasured, photo-reflectance of the cured test piece after being heatedin an oven at 150° C. for a prescribed time period was measured.

(3) LED Burn-in Test (Evaluation of Heat Resistance and LightResistance)

The cured test piece was fixed on an LED package mounted with a blue LED(tradename: OBL-CH2424, manufactured by GeneLite Inc.). The LED wasallowed to emit light by applying an electric current of 150 mA for oneweek at an environmental temperature of 60° C. Surface of the cured testpiece exposed to the LED light was visually checked and evaluatedaccording to the following criteria.

Good: no color change

Poor: Color of the irradiated surface changed to brown.

Example 1

Materials used in respective components were: 6.5 g of hydrogenatedpolyisoprene diacrylate (tradename: SPIDA, manufactured by Osaka OrganicChemical Industry, Ltd.) as the component (A) ((meth)acrylate having along-chain aliphatic hydrocarbon group); 3.5 g of 1-adamantylmethacrylate (tradename: Adamantate M-104, manufactured by IdemitsuKosan Co., Ltd.) as the component (B); 0.5 g of glycidyl methacrylate(manufactured by Wako Pure Chemical Industries, Ltd.) as the component(C); 0.1 g of 1,1-bis(t-hexylperoxy)cyclohexane (tradename: Perhexa HC,manufactured by NOF Corp.) as the component (D); and 1 g of titaniumdioxide (tradename: Tipaque PC-3, average particle diameter of 0.21 μm,manufactured by Ishihara Sangyo Kaisha, Ltd.) as the component (E).Firstly, the component (E) was added to the less viscous components (B),(C), and (D) and mixed using a planetary centrifugal mixer (tradename:Awatori-Rentaro, manufactured by Thinky Corp.). Then, the more viscouscomponent (A) was added to the mixture, and the resulting mixture wasstirred using the same mixer to obtain a composition.

This composition was applied on a metal plate for the adhesion test; andthen, this was piled up on another plate. After heating at 150° C. forone hour in an oven, the plate was cooled to room temperature to obtaina cured test piece for the adhesion test. Result of the adhesion test isshown in Table 1.

Example 2

A composition and a cured test piece were obtained by the method similarto that in Example 1 except that the amount of the component (C) waschanged to 1 g. Result of the adhesion test is shown in Table 1.

Example 3

A composition and a cured test piece were obtained by the method similarto that in Example 1 except that the amount of the component (C) waschanged to 2 g. Result of the adhesion test is shown in Table 1.

Example 4

A composition and a cured test piece were obtained by the method similarto that in Example 1 except that 1 g of 4-hydroxybutyl acrylate(tradename: 4HBA, manufactured by Nippon Kasei Chemical Co., Ltd.) wasused as the component (C). Result of the adhesion test is shown in Table1.

Comparative Example 1

A composition and a cured test piece were obtained by the method similarto that in Example 1 except that the component (C) was not used. Resultof the adhesion test is shown in Table 1.

TABLE 1 Comparative Example 1 Example 2 Example 3 Example 4 Example 1Component (A) Hydrogenated polyisoprene diacrylate (g) 6.5 6.5 6.5 6.56.5 (% by mass) *1 61.9% 59.1% 54.2% 59.1% 65.0% Component (B)1-Adamantyl methacrylate (g) 3.5 3.5 3.5 3.5 3.5 (% by mass) *1 33.3%31.8% 29.2% 31.8% 35.0% Component (C) Glycidyl methacrylate (g) 0.5 1 2— — (% by mass) *1 4.8% 9.1% 16.6% — — 4-Hydroxybutyl acrylate (g) — — —1 — (% by mass) *1 — — — 9.1% — Component (D)1,1-Bis(t-hexylperoxy)cyclohexane (g) 0.1 0.1 0.1 0.1 0.1 (parts bymass)*2 1.0 0.9 0.8 0.9 1.0 Component (E) Titanium dioxide (g) 1 1 1 1 1(parts by mass)*2 9.5 9.1 8.3 9.1 10.0 Adhesion Stress at maximum point(MPa) 5.5 7.4 10 5.8 3.3 *1: % by mass based on totality of thecomponents (A), (B) and (C) *2parts by mass relative to 100 parts bymass of totality of the components (A), (B) and (C)

As shown in Table 1, it was observed that the component (C) is effectivein adhesion with the lead frame material. Accordingly, it was found thatthe composition of the present invention provides a cured product havingthe excellent adhesion with adjacent parts (especially with the leadframe).

Example 5

Materials used in respective components were: 15 g of lauryl acrylate((meth)acrylate having a long-chain aliphatic hydrocarbon group;tradename: SR-335, manufactured by Sartomer, LLC) and 5 g ofpolyethylene glycol #400 dimethacrylate (polyalkyleneglycol(meth)acrylate having number-average molecular weight of not less than400; tradename: NK Ester 9G (molecular weight: 536), manufactured byShin-Nakamura Chemical Co., Ltd.) as the component (A); 25 g of1-adamantyl methacrylate (tradename: Adamantate M-104, manufactured byIdemitsu Kosan Co., Ltd.) as the component (B); 5 g of glycidylmethacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) asthe component (C); 0.5 g of 1,1-bis(t-hexylperoxy)cyclohexane(tradename: Perhexa HC, manufactured by NOF Corp.) as the component (D),and 0.25 g of antioxidant (tradename: IRGANOX 3114, chemical name:tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, manufactured by BASFSE); and 75 g of titanium dioxide (average particle diameter: 0.21 μm,tradename: Tipaque PC-3, manufactured by Ishihara Sangyo Kaisha, Ltd.)as the component (E). In this Example, because a highly viscous monomeris not contained, the components (A) to (D) and the antioxidant weremixed using a planetary centrifugal mixer (tradename: Awatori-Rentaro,manufactured by Thinky Corp.); and then, the component (E) was added tothe mixture, and the resulting mixture was stirred using the same mixerto obtain a composition.

Then, a spacer having 3 mm thickness made of tetrafluoroethylene and analuminum plate having 3 mm thickness were inserted between two steelplates in such a manner that the aluminum plate may be tucked in betweenthe steel plate and the spacer to make a cell. The above-mentionedcomposition was poured into the space of the cell, and the cell washeated in an oven at 150° C. for one hour, and then cooled to roomtemperature. The steel plates, the spacer, and the aluminum plate wereremoved to obtain a cured test piece composed of the composition.Measurement of the photo-reflectance and the LED burn-in test werecarried out using the cured test piece according to the methodsmentioned above. The results are shown in Table 2.

Example 6

Materials used in respective components were: 25 g of hydrogenatedpolybutadiene diacrylate (tradename: SPBDA-S30, manufactured by OsakaOrganic Chemical Industry, Ltd.) as the component (A); 22.5 g of1-adamantyl methacrylate (tradename: Adamantate M-104, manufactured byIdemitsu Kosan Co., Ltd.) as the component (B); 2.5 g of glycidylmethacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) asthe component (C); 1 g of 1,1-bis(t-hexylperoxy)cyclohexane (tradename:Perhexa HC, manufactured by NOF Corp.) as the component (D), and 0.25 gof Sumilizer GA-80 (tradename of3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undececane,manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 g of SumilizerTP-D (tradename of pentaerythritol tetrakis(3-laurylthiopropionate),manufactured by Sumitomo Chemical Co., Ltd.) as the antioxidants; and 35g of titanium dioxide (tradename: Tipaque PC-3, manufactured by IshiharaSangyo Kaisha, Ltd.) as the component (E). Firstly, the component (E)was added to the less viscous components (B) to (D) and antioxidants andmixed using a planetary centrifugal mixer (tradename: Awatori-Rentaro,manufactured by Thinky Corp.). Then, the more viscous component (A) wasadded to the mixture, and the resulting mixture was stirred using thesame mixer to obtain a composition.

A cured test piece was obtained by the method similar to that in Example5 except that this composition was used; and then, measurement of thephoto-reflectance and the LED burn-in test were carried out. The resultsare shown in Table 2.

Example 7

Materials used in respective components were: 25 g of hydrogenatedpolyisoprene diacrylate (tradename: SPIDA, manufactured by Osaka OrganicChemical Industry, Ltd.) as the component (A); 22.5 g of 1-adamantylmethacrylate (tradename: Adamantate M-104, manufactured by IdemitsuKosan Co., Ltd.) as the component (B); 2.5 g of glycidyl methacrylate(manufactured by Wako Pure Chemical Industries, Ltd.) as the component(C); 1 g of 1,1-bis(t-hexylperoxy)cyclohexane (tradename: Perhexa HC,manufactured by NOF Corp.) as the component (D), and 0.25 g of SumilizerGA-80 (tradename, manufactured by Sumitomo Chemical Co., Ltd.) and 0.25g of Sumilizer TP-D (tradename, manufactured by Sumitomo Chemical Co.,Ltd.) as the antioxidants; and 5 g of titanium dioxide (tradename:Tipaque PC-3, manufactured by Ishihara Sangyo Kaisha, Ltd.) as thecomponent (E). These compounds were mixed in the same order as Example 6to obtain a composition.

A cured test piece was obtained by the method similar to that in Example5 except that this composition was used; and then, measurement of thephoto-reflectance and the LED burn-in test were carried out. The resultsare shown in Table 2.

Example 8

A composition was obtained by the method similar to that in Example 7except that 12.5 g of the component (E) was used in Example 7.

A cured test piece was obtained by the method similar to that in Example5 except that this composition was used; and then, measurement of thephoto-reflectance and the LED burn-in test were carried out. The resultsare shown in Table 2.

Example 9

Materials used in respective components were: 15 g of lauryl acrylate(tradename: SR335, manufactured by Sartomer, LLC) and 10 g ofethoxylated (9) trimethylolpropane triacrylate (tradename: SR-502,molecular weight: 692, manufactured by Sartomer, LLC) as the component(A); 22.5 g of 1-adamantyl methacrylate (tradename: Adamantate M-104,manufactured by Idemitsu Kosan Co., Ltd.) as the component (B); 2.5 g ofglycidyl methacrylate (manufactured by Wako Pure Chemical Industries,Ltd.) as the component (C); 0.5 g of 1,1-bis(t-hexylperoxy)cyclohexane(tradename: Perhexa HC, manufactured by NOF Corp.) as the component (D),and 0.25 g of Sumilizer GA-80 (tradename, manufactured by SumitomoChemical Co., Ltd.) and 0.25 g of Sumilizer TP-D (tradename,manufactured by Sumitomo Chemical Co., Ltd.) as the antioxidants; and 50g of titanium dioxide (tradename of Tipaque PC-3, manufactured byIshihara Sangyo Kaisha, Ltd.) as the component (E). These compounds weremixed in the same order as Example 5 to obtain a composition.

A cured test piece was obtained by the method similar to that in Example5 except that this composition was used; and then, measurement of thephoto-reflectance and the LED burn-in test were carried out. The resultsare shown in Table 2.

Example 10

Materials used in respective components were: 25 g of dual-end reactivesilicone oil (tradename: X-22-164E, manufactured by Shin-Etsu ChemicalCo., Ltd.) as the component (A); 22.5 g of 1-adamantyl methacrylate(tradename: Adamantate M-104, manufactured by Idemitsu Kosan Co., Ltd.)as the component (B); 2.5 g of glycidyl methacrylate (manufactured byWako Pure Chemical Industries, Ltd.) as the component (C); 0.5 g of1,1-bis(t-hexylperoxy)cyclohexane (tradename: Perhexa HC, manufacturedby NOF Corp.) as the component (D), and 0.25 g of Sumilizer GA-80(tradename, manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 g ofSumilizer TP-D (tradename, manufactured by Sumitomo Chemical Co., Ltd.)as the antioxidants; and 5 g of titanium dioxide (tradename of TipaquePC-3, manufactured by Ishihara Sangyo Kaisha, Ltd.) as the component(E). These compounds were mixed in the same order as Example 6 to obtaina composition.

A cured test piece was obtained by the method similar to that in Example5 except that this composition was used; and then, measurement of thephoto-reflectance and the LED burn-in test were carried out. The resultsare shown in Table 2.

Comparative Example 2

Measurement of the photo-reflectance and the LED burn-in test werecarried out using a plate of white polyphthalamide resin (tradename:AMODEL A-4122NL, manufactured by Solvay Advanced Polymers, LLC). Theresults are shown in Table 2.

Comparative Example 3

Materials used in respective components were: 2.5 g of hydrogenatedpolyisoprene diacrylate (tradename: SPIDA, manufactured by Osaka OrganicChemical Industry, Ltd.) as the component (A); 46.5 g of 1-adamantylmethacrylate (tradename: Adamantate M-104, manufactured by IdemitsuKosan Co., Ltd.) as the component (B); 1.0 g of glycidyl methacrylate(manufactured by Wako Pure Chemical Industries, Ltd.) as the component(C); 1 g of 1,1-bis(t-hexylperoxy)cyclohexane (tradename: Perhexa HC,manufactured by NOF Corp.) as the component (D), and 0.25 g of SumilizerGA-80 (tradename, manufactured by Sumitomo Chemical Co., Ltd.) and 0.25g of Sumilizer TP-D (tradename, manufactured by Sumitomo Chemical Co.,Ltd.) as the antioxidants; and 5 g of titanium dioxide (tradename:Tipaque PC-3, manufactured by Ishihara Sangyo Kaisha, Ltd.) as thecomponent (E). These compounds were mixed in the same order as Example 6to obtain a composition.

When an attempt was made to obtain a cured test piece similarly toExample 5 except that this composition was used, only a cracked testpiece was obtained so that it could not be evaluated.

Comparative Example 4

Materials used in respective components were: 25 g of triethylene glycoldimethacrylate (tradename: NK Ester 3G, molecular weight: 286,manufactured by Shin-Nakamura Chemical Co., Ltd.), which does notcorrespond to the component (A); 22.5 g of 1-adamantyl methacrylate(tradename: Adamantate M-104, manufactured by Idemitsu Kosan Co., Ltd.)as the component (B); 2.5 g of glycidyl methacrylate (manufactured byWako Pure Chemical Industries, Ltd.) as the component (C); 0.5 g of1,1-bis(t-hexylperoxy)cyclohexane (tradename: Perhexa HC, manufacturedby NOF Corp.) as the component (D), and 0.25 g of Sumilizer GA-80(tradename, manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 g ofSumilizer TP-D (tradename, manufactured by Sumitomo Chemical Co., Ltd.)as the antioxidants; and 5 g of titanium dioxide (tradename: TipaquePC-3, manufactured by Ishihara Sangyo Kaisha, Ltd.) as the component(E). These compounds were mixed in the same order as Example 5 to obtaina composition.

When an attempt was made to obtain a cured test piece similarly toExample 5 except that this composition was used, only a cracked testpiece was obtained so that it could not be evaluated.

TABLE 2 Compar- Compar- Compar- ative ative ative Exam- Exam- Exam-Exam- Exam- Exam- Exam- Exam- Exam- ple 5 ple 6 ple 7 ple 8 ple 9 ple 10ple 2 ple 3 ple 4 Compo- Dual-end reactive silicone oil (g) — — — — — 25White — — nent (A) (% by mass) *1 — — — — — 50% Poly- — — Laurylacrylate (g) 15 — — — 15 — phthalamide — — (% by mass) *1 30% — — — 30%— resin — — Polyethylene glycol #400 5 — — — — — — — dimethacrylate (g)(% by mass) *1 10% — — — — — — — Hydrogenated polybutadiene diacrylate(g) — 25 — — — — — — (% by mass) *1 — 50% — — — — — — Hydrogenatedpolyisoprene diacrylate (g) — — 25 25 — — 2.5 — (% by mass) *1 — — 50%50% — — 5% — Ethoxylated (9) trimethylolpropane — — — — 10 — — —triacrylate (g) (% by mass) *1 — — — — 20% — — — Triethylene glycoldimethacrylate (g) 25 (% by mass) *1 50% Compo- 1-Adamantyl methacrylate(g) 25 22.5 22.5 22.5 22.5 22.5 46.5 22.5 nent (B) (% by mass) *1 50%45% 45% 45% 45% 45% 93%  45% Compo- Glycidyl methacrylate (g) 5 2.5 2.52.5 2.5 2.5 1 2.5 nent (C) (% by mass) *1 10%  5%  5%  5%  5%  5% 2%  5%Compo- 1,1-Bis(t-hexylperoxy)cyclohexane (g) 0.5 1 1 1 0.5 0.5 1 0.5nent (D) (parts by mass)*2 1 2 2 2 1 1 2 1 Anti- IRGANOX 3114 (g) 0.25 —— — — — — — oxidant Sumilizer GA-80 (g) — 0.25 0.25 0.25 0.25 0.25 0.250.25 Sumilizer TP-D (g) — 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Compo-Titanium dioxide (g) 75 35 5 12.5 50 5 5 5 nent (E) (parts by mass)*2150 70 10 25 100 10 10 10 Photo-reflectance (%) Initial 98 98 98 99 9998 90 Unevalu- Unevalu- (450 nm) After 168 hours — — — — — — 57 ableable at 150° C. After 1000 hours 93 95 94 96 96 95 — at 150° C. Heatresistance and light resistance Good Good Good Good Good Good PoorIRGANOX 3114: trade name, manufactured by BASF SE Sumilizer GA-80: tradename, manufactured by Sumitomo Chemical Co., Ltd. Sumilizer TP-D: tradename, manufactured by Sumitomo Chemical Co., Ltd. *1: % by mass based ontotality of the components (A), (B) and (C) *2parts by mass relative to100 parts by mass of totality of the components (A), (B) and (C)

As can be seen in Table 2, in Comparative Example 2 in which whitepolyphthalamide resin was used, initial value of the photo-reflectancewas 90%, which was decreased to 57% after 168 hours at 150° C. Inaddition, color of the irradiated surface was changed to brown after theLED burn-in test. In Comparative Example 3 in which content of thecomponent (A) was too small and in Comparative Example 4 in whichpolyalkylene glycol (meth)acrylate having number-average molecularweight of not more than 400, which does not correspond to the component(A), was used, flexibility could not be obtained because contribution ofthe component (A) was too small. On the contrary, in Examples 5 to 10 inwhich compositions of the present invention were used, not only theinitial values of photo-reflectance (98 to 99%), but also the valueseven after 1,000 hours at 150° C. were high (93 to 96%). In addition,there was no color change after the LED burn-in test. Accordingly, itwas concluded that the composition of the present invention can providea cured product having high reflectance in the visible light regionwithout decrease of the reflectance even after a long-term usage, andhaving the excellent heat resistance and light resistance with lessyellowing.

INDUSTRIAL APPLICABILITY

The (meth)acrylate composition of the present invention can provide acured product having high reflectance in the visible light region withthe excellent whiteness, heat resistance, and light resistance, and withless yellowing, and in addition, having the excellent adhesion withadjacent parts (especially with the lead frame); and thus, thecomposition can be used suitably as a raw material of a reflectivematerial for an optical semiconductor.

The reflective material made using the cured product obtained by curingthe (meth)acrylate composition of the present invention does notdecrease in its reflectance even after a long-term usage, while havinghigh reflectance in the visible light region and the excellent adhesionwith adjacent parts. The reflective material of the present inventionmay be used for a lamp reflector of a liquid crystal display, areflective board of a showcase, a reflective board of variousillumination apparatuses, a reflective material for LED, and so on.Specific examples of a photoelectric conversion element containing thereflective material of the present invention and a photoelectricconversion device containing the photoelectric conversion elementinclude various OA equipment, electric and electronic equipment andparts thereof, and automobile parts, such as a display, a destinationsign board, a car lamp, a signal light, an emergency light, a cellphone, and a video camera.

1. A (meth)acrylate composition comprising: (A) at least one(meth)acrylate compound selected from the group consisting of a(meth)acrylate-modified silicone oil, a (meth)acrylate comprising along-chain aliphatic hydrocarbon group, and a polyalkylene glycol(meth)acrylate having number-average molecular weight of not less than400, (B) a (meth)acrylate compound ester-linked to an alicyclichydrocarbon group having 6 or more carbon atoms, (C) (meth)acrylic acidor a (meth)acrylate compound comprising a polar group, (D) a radicalpolymerization initiator, and (E) a white pigment.
 2. The (meth)acrylatecomposition according to claim 1, wherein an amount of the at least one(meth)acrylate compound (A) is from 5 to 90% by mass, an amount of the(meth)acrylate compound ester-linked to an alicyclic hydrocarbon group(B) is from 5 to 90% by mass, and an amount of the (meth)acrylic acid or(meth)acrylate compound (C) is from 0.5 to 50% by mass, based on atotality of components (A), (B) and (C), and an amount of the radicalpolymerization initiator (D) is from 0.01 to 10 parts by mass and anamount of the white pigment (E) is from 3 to 200 parts by mass, relativeto 100 parts by mass of a totality of the components (A), (B) and (C).3. The (meth)acrylate composition according to claim 1, wherein the atleast one (meth)acrylate compound (A) is a (meth)acrylate having analiphatic hydrocarbon group with 12 or more carbon atoms, a polyalkyleneglycol (meth)acrylate having number-average molecular weight of not lessthan 400, or any combination thereof.
 4. The (meth)acrylate compositionaccording to claim 1, wherein the at least one (meth)acrylate compound(A) is a hydrogenated polybutadiene di(meth)acrylate, hydrogenatedpolyisoprene di(meth)acrylate, a polyethylene glycol di(meth)acrylatehaving number-average molecular weight of not less than 400, or anycombination thereof.
 5. The (meth)acrylate composition according toclaim 1, wherein the (meth)acrylate compound ester-linked to analicyclic hydrocarbon group (B) is a (meth)acrylate compoundester-linked with at least one alicyclic hydrocarbon group selected fromthe group consisting of adamantyl, norbornyl, isobornyl,dicyclopentanyl, and cyclohexyl.
 6. The (meth)acrylate compositionaccording to claim 1, wherein the (meth)acrylic acid or (meth)acrylatecompound (C) is a (meth)acrylate compound comprising a polar groupselected from the group consisting of hydroxyl, epoxy, glycidyl ether,tetrahydrofurfuryl, isocyanate, carboxyl, alkoxysilyl, phosphate ester,lactone, oxetane, and tetrahydropyranyl.
 7. A cured product obtained bya process comprising curing the (meth)acrylate composition according toclaim
 1. 8. A reflective material comprising the cured product accordingto claim
 7. 9. The reflective material according to claim 8, wherein thereflective material is suitable for an optical semiconductor.
 10. The(meth)acrylate composition according to claim 3, wherein the(meth)acrylate compound ester-linked to an alicyclic hydrocarbon group(B) is a (meth)acrylate compound ester-linked with at least onealicyclic hydrocarbon group selected from the group consisting ofadamantyl, norbornyl, isobornyl, dicyclopentanyl, and cyclohexyl. 11.The (meth)acrylate composition according to claim 3, wherein the(meth)acrylic acid or (meth)acrylate compound (C) is a (meth)acrylatecompound comprising a polar group selected from the group consisting ofhydroxyl, epoxy, glycidyl ether, tetrahydrofurfuryl, isocyanate,carboxyl, alkoxysilyl, phosphate ester, lactone, oxetane, andtetrahydropyranyl.
 12. The (meth)acrylate composition according to claim10, wherein the (meth)acrylic acid or (meth)acrylate compound (C) is a(meth)acrylate compound comprising a polar group selected from the groupconsisting of hydroxyl, epoxy, glycidyl ether, tetrahydrofurfuryl,isocyanate, carboxyl, alkoxysilyl, phosphate ester, lactone, oxetane,and tetrahydropyranyl.